The background of the invention will be discussed in two parts:
1. Field of the Invention
This invention relates to aircraft batteries, and more particularly to a lead-acid aircraft battery encased in an aluminum housing.
2. Description of the Prior Art
In prior art aircraft batteries, conventionally a lead-acid battery is placed within an aluminum housing having side walls slightly greater than the overall height of the battery casing. Each of the cell apertures includes a neck portion extending above the battery casing cover, and for sealing the battery casing within the aluminum housing, in prior art techniques, the casing cover is flooded with an epoxy to the edge of the neck or sleeve of the cell aperture, thus providing an epoxy layer completely covering the battery casing cover.
In such prior art aircraft batteries, the casing of the battery is formed from a thick-walled carbon impregnated rubber composition configured for snug fitting relation within the aluminum housing, and an aluminum cover fitted over the aluminum housing to thereby provide an integral unit. The selection of materials for the casing and housing is usually made on the basis of coefficient of thermal expansion of the two materials, it being desirable that the coefficients be identical if not substantially similar.
However, with such prior art aircraft batteries, due to the extreme temperature environment within which the battery must operate, separation of the epoxy from the housing as well as the casing from the epoxy resulted, thereby endangering the mechanical and electrical integrity of the airplane system as a whole. While the coefficients of thermal expansion of the carbon impregnated rubber of the casing and the aluminum housing are generally similar, it is believed that this separation results from thermal shock or the like. With a generally thin walled aluminum, that is, thin as contrasted to the thick wall of the casing, it appears that the thermal conductivity of the aluminum is able to absorb sudden and extreme variations in temperature while the carbon impregnated rubber composition acted as a heat sink, thereby resulting in separation.
Another attendant disadvantage to the conventional thick walled carbon impregnated rubber casing is the addition of weight to the aircraft, the rubber casing of a typical aircraft battery weighing approximately 3.6 kilograms.
It is an object of the present invention to provide a new and improved lead-acid aircraft battery.
It is another object of the present invention to provide a new and improved light weight lead-acid aircraft battery.
It is still another object of the present invention to provide a new and improved sealing arrangement for securing the casing of a lead-acid aircraft battery to the aluminum housing thereof.